1. Field
The invention is in the field of venipuncture needles whose puncture points protrude from respective catheters which are to be placed in a vein punctured by the needle, and relates particularly to such venipuncture needle/catheter combinations in which the needle is retractable, following catheter placement, as a safety precaution against accidental pricking of the user following use, as well as to prevent reuse of a contaminated needle.
2. Prior Art
The prior art in this field is well-developed so far as needle retractability is concerned, but is very limited from the standpoint of automatic release of the needle for retraction following venipuncture and placement of the catheter in the vein.
An early patent to George O. Doherty, Missoula, Mont., U.S. Pat. No. 4,160,450 of Jul. 10, 1979, discloses venipuncture needle retractability within a safety chamber formed as a needle-receiving portion of the catheter.
Several later patents to Edward D. Dysarz of Houston, Tex., namely, U.S. Pat. No. 4,973,316 of Nov. 27, 1990, U.S. Pat. No. 5,125,414 of Jun. 30, 1992, and U.S. Pat. No. 5,129,884 of Jul. 14, 1992, disclose various arrangements for retracting an intravenous needle in an hypodermic syringe by spring action, as does a patent to Douglas Couvertier, II of Fort Lauderdale, Fla., U.S. Pat. No. 5,092,853, issued Mar. 3, 1992. The latter also purports to show embodiments of a device for placing a catheter in a vein.
Despite these developments in the field of medical needle retractability for safety purposes, there remains a need for preventing withdrawal of the needle from the catheter before activating needle release mechanism and while allowing the catheter to be maneuvered back and forth along and around the needle to facilitate deep placement of the catheter in the vein.